Distance and Displacement 11.1

Frame of Reference Objects are not moving with respect to one another Needed to accurately describe motion What is your frame of reference? You are on the earth…the earth is spinning on its axis and revolving around the sun, therefore you are moving even when you are standing still

Relative Motion Movement in relation to a frame of reference People at the train station see a train speeding by. But people on the train aren’t moving at all, relative to each other

Distance The length between 2 points Units are meter and kilometer

Displacement The length of a straight line from the starting point to the ending point It also includes direction If you travel in a circle, your displacement is zero.

Combining Displacements Displacement is an example of a vector- a quantity that has magnitude and direction Magnitude can be size, length or amount Arrows on a graph represent vectors You can add displacements using vector addition Pg 330 Figure 3

When two displacements- represented by vectors- have the same direction, you can add their magnitudes- Figure 3A When they are in opposite directions, you subtract their magnitudes- Figure 3B

Resultant Vectors If the displacement- starting point to ending point- is not along a straight path, you use vector addition to find the resultant vector Page 331 Figure 4 Page 331 # 1-3,5